Preheat the oven to 425 F.

Line a rimmed baking sheet with parchment paper.

Mince one of the jalapeños and slice the second one.

In a large sized mixing bowl, whisk together the flour, baking powder and salt.

Add in the diced butter and using a pastry blender or your fingers, work the butter into the flour mixture until it resembles course sand with just a few pea sized pieces of butter.

In a small mixing bowl, mix the sourdough starter and milk together.

Stir the shredded cheddar cheese and minced jalapeño into the flour and butter mixture.

Stir the milk mixture into the flour mixture until just barely combined.

Dump the mixture out onto a well floured surface and use your fingers to pat into a rectangle.

Fold the dough into thirds, envelope style.

Rotate the dough 90 degrees and pat out into a rectangle again.

Fold the dough into thirds a second time.

Rotate the dough 90 degrees and pat out into a rectangle for a second time.

Fold the dough into thirds for a third time.

Rotate the dough 90 degrees and pat out into a rectangle for a third time, this time patting it out until the dough is about 1 inch thick and has mostly straight edges.

Using a sharp knife, cut the dough into a 3x4 grid, making 12 biscuits. Cut straight down without dragging the knife through the dough.

Arrange the biscuits on the prepared baking sheet.

Brush the tops of the biscuits with a small amount of milk and top with a thin slice of jalapeño.

Bake for 12-15 minutes, until the tops are golden brown.

Cool for a few minutes before serving.